Multi-stage refrigerant turbine

ABSTRACT

A multi-stage refrigerant driven turbine is incorporated into a closed loop system to generate electricity. Heat transfer conduits and optional flow diverting members are disposed between the rotor blades of each stage of the turbine. The closed loop system also includes a condenser, pump, refrigerant storage container, refrigerant, and expansion valve. A heat source and heat sink are also provided. The expansion valve introduces a saturated refrigerant mist into the turbine, and the refrigerant expands as it flashes to a gas, thereby rotating the rotor blades and turbine shaft. Heat from the heat source is added between stages to increase the portion of refrigerant converted to gas. The gas is passed from the turbine, condensed, and passed as a liquid to storage or to repeat the cycle. The blending of refrigeration cycle and turbine technologies allows electricity to be generated in a closed loop system under moderate conditions.

BACKGROUND OF THE INVENTION

The present invention relates to electricity generation using a turbine and, more particularly, to electricity generation using a multi-stage turbine.

There has long been a desire to find alternative sources for generating electricity. Solar power panels are known in the art but are limited in their use, because they generate DC power only. Windmills are also well known in the art and have been used for generating AC power. Still, difficulties in finding appropriate locations for windmills, and fluctuations in wind force and direction limit their use and reliability.

Turbines and multi-stage turbines are known in the art. In gas turbines, compressed air is forced into an ignition chamber and combined with fuel, and the fuel is ignited. The expanding, ignited gases travel along the axis of the turbine shaft, imparting motion to rotor blades affixed to the turbine shaft, thereby rotating the shaft. Additional fuel, or after burner fuel, is sometimes added downstream of the ignition chamber to increase the power output. In steam turbines, water is boiled to generate steam, the steam is passed through a throttle valve, and the expanding steam travels along the axis of the turbine shaft, imparting motion to rotor blades affixed to the turbine shaft, thereby rotating the shaft. Additional steam is sometimes added downstream of the throttle valve to increase the power output. Gas turbines and steam turbines are capable of generating reliable A/C power but suffer from a number of disadvantages. For example, these turbines require fuels that are non-renewable or that are not readily renewable. The extreme conditions typically encountered in these turbines also adds to the cost and complexity of the equipment and materials of construction that must be used. These extreme conditions also lead to high maintenance cost, increased wear and tear, and short equipment life. The high energy input needed to maintain the extreme conditions also leads to high cost for power generation.

Refrigeration cycles are also well known in the art. In a typical refrigeration cycle, a refrigerant gas is compressed and passed to a heat sink or condenser. As the heat sink removes heat from the high temperature, high pressure gas, the gas condenses to liquid form. The condensed liquid is passed through an expansion valve so that it moves from a high pressure area to a low pressure area. As the liquid moves from through the expansion valve, the liquid expands and evaporates. The expanding, evaporating gas is passed to a heat source, such as an interior of a refrigerator or freezer. The heat required to convert the liquid to gas is drawn from the heat source, thereby cooling the heat source. The refrigerant gas is then returned to the compressor to repeat the cycle. Refrigeration cycles have provided reliable cooling for years. Still, the use of a compressor in a refrigeration cycle increases the cost and complexity of the system and also increases the energy consumption and therefore operation cost of the system. Using a compressor can also add to the cost and complexity of maintaining a refrigeration cycle.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an apparatus and method for efficiently generating electricity.

It is a further object of the present invention to provide an apparatus and method of the above type that is capable of using a wide variety of heat sources and heat sinks to provide a reliable source of A/C power.

It is a still further object of the present invention to provide an apparatus and method of the above type that generates A/C power using solar energy.

It is a still further object of the present invention to provide an apparatus and method of the above type that combines turbine technology and refrigeration cycle technology to provide a safe and efficient way of generating electricity.

It is a still further object of the present invention to provide an apparatus and method of the above type that uses a refrigerant to drive a turbine.

It is a still further object of the present invention to provide an apparatus and method of the above type that uses a refrigerant to drive a multi-stage turbine.

It is a still further object of the present invention to provide an apparatus and method of the above type that offers an environmentally friendly way to generate electricity.

It is a still further object of the present invention to provide an apparatus and method of the above type that operates under more moderate conditions than traditional turbines.

It is a still further object of the present invention to provide an apparatus and method of the above type that operates without the need for the added cost and complexity of a compressor such as typically used in a refrigeration cycle.

It is a still further object of the present invention to provide an apparatus and method of the above type that provides a safe, efficient closed loop system for generating electricity.

It is a still further object of the present invention to provide an apparatus and method of the above type that may be constructed using less costly materials of construction because of the more moderate operating conditions.

It is a still further object of the present invention to provide an apparatus and method of the above type that provides for reduced operating and maintenance expenses and for increased operating life.

It is a still further object of the present invention to provide an apparatus and method of the above type that makes efficient use of waste heat from other processes.

It is a still further object of the present invention to provide an apparatus and method of the above type that allows waste heat from a wide variety of sources to be used to provide a reliable source of A/C power.

Toward the fulfillment of these and other objects and advantages, the present invention comprises a multi-stage, refrigerant driven turbine, a closed loop system into which it is incorporated, and a method of operating the system. A multi-stage refrigerant driven turbine is incorporated into a closed loop system to generate electricity. Heat transfer conduits and optional flow diverting members are disposed between the rotor blades of each stage of the turbine. The closed loop system also includes a condenser, pump, refrigerant storage container, refrigerant, and expansion valve. A heat source and heat sink are also provided. The expansion valve introduces a saturated refrigerant mist into the turbine, and the refrigerant expands as it flashes to a gas, thereby rotating the rotor blades and turbine shaft. Heat from the heat source is added between stages to increase the portion of refrigerant converted to gas. The gas is passed from the turbine, condensed, and passed as a liquid to storage or to repeat the cycle. The blending of refrigeration cycle and turbine technologies allows electricity to be generated in a closed loop system under moderate conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The above brief description, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of the presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a schematic representation of a system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, reference numeral 10 refers in general to a refrigerant system of the present invention. The system includes an expansion valve 12, a turbine 14, a condenser 16, a pump 18, and refrigerant 20 and may include a refrigerant storage reservoir or container 22. A heat source 24 and heat sink 26 are also provided.

The expansion or throttling valve 12 of the refrigerant system 10 may take the form of any number of different commercially available throttle valves or spray nozzles. The valve 12 has speed or load governing controls, and the size and capacity of the valve depend upon a variety of system parameters, such as size and operating conditions. Multiple valves 12 may be used and may be positioned at different locations to help control load. The valve 12 may also admit refrigerant 20 directly to the turbine 14, or may admit the refrigerant to an evaporator or heat exchanger before the refrigerant 20 is passed to the turbine 14.

In a preferred embodiment, the turbine 14 is an axial flow, multi-stage turbine. The housing or casing 28 has a front, upstream end 30 and a rear, downstream end 32. An outer wall of the housing 28 generally diverges from front to back. A turbine shaft 34 is disposed partially within the housing 28, and rotor blades 36 a, 36 b, 36 c are affixed to the shaft 34, positioned along the length of the shaft 34 so that they are disposed in different stages of the turbine 14. Steam turbines operating at relatively high velocities, pressures, and temperatures are subject to blade impingement from entrained moisture in the steam, and rotor blades can be permanently damaged by the water. As a result, rotor blades in steam turbines must be of very rugged construction, placing significant restrictions on the types of materials from which the blades may be constructed. In contrast, due to the relatively modest velocities, pressures and temperatures in which the present turbine 14 should operate many fewer restrictions are placed on the materials of construction of the rotor blades 36 a, 36 b, 36 c and other components. The rotor blades 36 a, 36 b, and 36 c may be constructed of any number of materials, including but not limited to aluminum, composites, plastics, or various blends or combinations of those and other components. For example, the blades 36 a, 36 b, and 36 c may comprise at least approximately 20% of a material selected from the group consisting of aluminum, composites, plastics, and combinations thereof. Further, because of the more moderate operating conditions, the rotor blades 36 a, 36 b, and 36 c will not require the closely machined tolerances or shrouded blade tips typically required in steam turbines. The turbine 14 stages and reduction gearing may be arranged as in any conventional turbine design, with the number of stages and the reduction ratio dependent upon the specific system flow capabilities. Due to the relatively moderate temperatures within the turbine 14, the reduction gears may be disposed within the housing between each stage.

An axially aligned, frustoconical inner turbine wall 38 a diverging from front to back is positioned in close proximity to the rotor blades 36 a in the first stage of the turbine 14. Each rotor blade 36 a extends a distance radially from the shaft 34, and that distance increases with distance from the front of the stage so that an outer edge of each rotor blade 36 a is maintained in close proximity to the diverging inner turbine wall 38 a. The rear end of the first diverging turbine wall 38 a is aligned at or near the last rotor blade 36 a of the first stage.

A flow diverting member 40 a is centrally positioned in the housing, disposed between the rotor blades 36 a of the first stage and the rotor blades 36 b of the second stage, the shaft 34 passing through an opening in the member 40 a. Front portions of the member 40 a are disposed between the inner turbine wall 38 a and the outer turbine wall 28, and forward portions of the member 40 a extend forward and downstream of the back end of the inner wall 38 a and forward and downstream of at least one of the rotor blades 36 a in the first stage. The flow diverting member 40 a is affixed within the turbine 14 so that it does not move relative to the inner turbine wall 38 a.

Heat transfer conduits 42 a, 42 b, and 42 c, such as a tube bank, are disposed along or within the turbine 14 between each stage to create a regeneration area. In a preferred embodiment, tubes extend into the flow path of the refrigerant 20, aligned generally transverse to the flow path. It is of course understood that the conduits 42 a, 42 b, and 42 c may take any number of forms, such as one or more tubes or jackets lining the housing or extending into the flow path within the housing 28. The heat transfer conduits 42 a, 42 b, and 42 c will typically be sized and disposed to provide for greater heat transfer to later stages within the turbine 14. The regeneration areas assist in eliminating the need for a compressor, as is typically used in convention refrigeration cycles. The use of saturated vapor and regeneration areas helps to compensate for the low enthalpy of the refrigerant 20 as compared to steam.

A second axially aligned, frustoconical inner turbine wall 38 b diverging from front to back is positioned in close proximity to the rotor blades 36 b in the second stage of the turbine 14. Each rotor blade 36 b in the second stage extends a distance radially from the shaft 34, and that distance increases with distance from the front of the stage so that an outer edge of each rotor blade 36 b is maintained in close proximity to the diverging inner turbine wall 38 b. The rear end of the second diverging turbine wall 38 b is aligned at or near the last rotor blade 36 b of the second stage. The rotor blades 36 b of the second stage generally extend a greater distance radially from the axis than do the rotor blades 36 a of the first stage.

A second flow diverting member 40 b is centrally positioned in the housing 28, disposed between the rotor blades 36 b of the second stage and the rotor blades 36 c of the third stage, the shaft 34 passing through an opening in the member 40 b. Front portions of the member 40 b are disposed between the inner turbine wall 38 b and the outer turbine wall 28, and forward portions of the member 40 b extend forward and downstream of the back end of the inner wall 38 b and forward and downstream of at least one of the rotor blades 36 b in the second stage.

Similar to the regeneration area between the first and second stages, heat transfer conduits 42 b, such as a tube bank, are disposed along or within the turbine 14 between the second and third stages to create a second regeneration area.

Additional stages are provided as needed. For example, another axially aligned, frustoconical inner turbine wall 38 c diverging from front to back is positioned in close proximity to the rotor blades 36 c in the third stage of the turbine 14. Each rotor blade 36 c in the third stage extends a distance radially from the shaft 34, and that distance increases with distance from the front of the stage so that an outer edge of each rotor blade 36 c is maintained in close proximity to the diverging inner turbine wall 38 c. The rear end of the third diverging turbine wall 38 c is aligned at or near the last rotor blade 36 c of the third stage. The rotor blades 36 c of the third stage generally extend a greater distance radially from the axis than do the rotor blades 36 a and 36 b of the first and second stages. Additional flow diverting members and regeneration areas are provided for the additional stages as needed.

It is of course understood that most common turbine designs may be used, including but not limited to radial flow, axial flow, horizontal, vertical, and with or without pressure and velocity compounding. Casing or housing pressure requirements will depend on factors such as the type of refrigerant 20 used and the maximum operational pressures and temperatures expected. The casing may also be designed as a hermetic unit with an internal casing dividing the stages rated at system differential pressure, and an outer casing rated at overall system pressure.

The downstream or discharge end of the multistage turbine 14 is connected to a condenser 16. The condenser 16 may take the form of any number of commercially available condensers. The condenser 16 is sized for the expected operating parameters of the particular system to provide sufficient heat transfer to condense the refrigerant gas into liquid. The condenser 16 cooling may be of the direct type, in which the refrigerant 20 in the closed loop system is cooled directly by the heat sink 26, or of the indirect type, in which a cooling medium such as water is used to transfer heat between the condenser 16 and the heat sink 26. As used herein, “direct” cooling or heating is not intended to mean or imply direct contact between the refrigerant 20 and the heating or cooling fluid. Under rare circumstances, such direct contact or commingling may be used, but not in the preferred embodiment.

A line 44 connects the condenser 16 to the refrigerant reservoir 22, and a feed pump 18 is provided in the line 44 for transferring liquid refrigerant 20 to the reservoir 22 or expansion valve 12, depending on system load requirements. The pump 18 is sized as needed to meet the pressure and flow requirements of the particular system. The refrigerant 20 may take the form of any number of different commercially available refrigerants. The refrigerant 20 preferably has a boiling point at 14.7 psi that is less than or equal to approximately 10° F. and more preferably has a boiling point at 14.7 psi that is less than or equal to approximately 32° F. The refrigerant 20 is most preferably selected from the group consisting of R-11, R-12, R-13, R-134 a, R-142 b, R-152A, R-290, R-410 a, R-404 a, R-600, R-600 a, a hydrofluorocarbon, a chlorofluorocarbon, CO₂, ammonia, nitrogen, freon, and combinations thereof. Because of the refrigerant or refrigerants being used, the refrigerant system 10 is preferably a closed loop system. The refrigerant system 10 may be designed as hermetic or semi-hermetic depending upon the application.

The heat source or heating system 24 is preferably an indirect heat collection system 24 that uses a secondary medium, such as water, to collect and transfer heat from the heat source 24 to the refrigerant system 10. The heating system 24 is connected to the heat transfer conduits 42 a, 42 b, and 42 c in the refrigerant system 10. The heating system 24 will have relatively moderate operating conditions. For example, there are relatively low pressure requirements since the transfer medium is merely circulating. Accordingly, lower cost materials, such as plastic and PVC pipe and tubing may be used. Using this indirect heating system 24 allows great flexibility in positioning and configuring the refrigerant system 10 relative to the heat source 24.

The heat source 24 may take any number of forms ranging from solar panels to a heat exchanger used to dissipate or disperse waste heat from large-scale industrial activities. Any number of different conventional sources of heat, or combinations thereof, may be used, including heat sources 24 that have heretofore not been used for generating AC power. Water is preferably used to acquire heat from the heat source 24 and to transfer that heat to the refrigerant 20 in the refrigerant system 10. Pump 46 circulates the water between the heat source 24 and the heat transfer conduits 42 a, 42 b, and 42 c of the refrigerant system 10.

The heat sink or cooling system 26 is preferably an indirect heat collection system that uses a secondary medium, such as water, to absorb heat from the condenser 16 and transfer it to the heat sink 26. The heat sink 26 is connected to the cooling coils 48 in the condenser 16. The cooling system 26 will have relatively moderate operating conditions. For example, there are relatively low pressure requirements since the transfer medium is merely circulating. Accordingly, lower cost materials, such as plastic and PVC pipe and tubing may be used. Using this indirect cooling system 26 allows great flexibility in positioning and configuring the refrigerant system 10 relative to the heat sink 26.

The heat sink 26 may take any number of forms such as reservoirs, streams, bodies of water, the atmosphere, buried pipes, cooling towers, other things and systems typically used to dissipate or disperse heat, and combinations thereof. Water is preferably used to absorb heat from the condenser 16 and to transfer that heat to the heat sink 26. Pump 50 circulates the water between the heat sink 26 and the condenser 16 of the refrigerant system 10.

In operation, pump 46 passes a heating medium, such as water, through line 52 and through the heat source 24. The water absorbs heat and passes through line 54 to the heat transfer conduits 42 a, 42 b, and 42 c, located in the regeneration areas of the refrigerant system 10, to transfer heat to the refrigerant 20 passing through the turbine 14. The water then passes through line 56 and back through the pump 46 to begin another cycle. It is of course understood that any number of heating systems 24 and heating mediums may be used and that any number of things may serve as the heat source 24.

Refrigerant 20 passes through the expansion or throttling valve 12 and expands through the diverging inner turbine wall 38 a as it flashes to a gas, thereby rotating the first set of rotor blades 36 a and the turbine shaft 34. The refrigerant 20 exits this first stage in the form of a heavily saturated mist. A first flow diverting member 40 a redirects the refrigerant 20 so that it passes downstream of but forward of at least one of the first set of rotor blades 36 a, through a first regeneration area. Heat transfer conduits 42 a in the first regeneration area transfer heat to the gas, increasing the portion of the refrigerant 20 that is converted to gas. Some of the entrained refrigerant droplets boil, or flash off into vapor before being directed through the second diverging inner turbine wall 38 b and through the second set of turbine blades 36 b. A second flow diverting member 40 b redirects the refrigerant 20 so that it passes downstream of but forward of at least one of the second set of rotor blades 36 b, through a second regeneration area. Heat transfer conduits 42 b in the second regeneration area transfer additional heat to the gas, increasing the portion of the refrigerant 20 that is converted to gas. The refrigerant 20 is then directed through the third diverging inner turbine wall 38 c and third set of turbine blades 36 c. Additional stages are used as desired. The rotating shaft 34 is used to perform work, such as to generate AC power. It is of course understood that the system may be used to generate DC power or to perform work in any number of different forms.

Upon leaving the final turbine stage, the refrigerant 20 is in the form of a high temperature, high pressure gas. The refrigerant 20 is then directed to the condenser 16. In the condenser 16, the water in the cooling coils 48 absorbs heat from the refrigerant 20 and transfers it to the heat sink 26. Sufficient heat is removed to cause the refrigerant 20 to condense into liquid form and gather at the bottom of the condenser 16. Feed pump 18 then transfers the liquid refrigerant 20 via line 44 to the reservoir 22 or back to the throttle valve 12, depending upon the load on the refrigerant system 10.

Pump 50 passes a cooling medium, such as water, through line 58 and through the cooling coils 48 of the condenser 16. The water absorbs heat in the condenser 16 and then passes through line 60 to the heat sink 26 for cooling. The water then passes through line 62 and back through the pump 50 to begin another cooling cycle. It is of course understood that any number of cooling systems 26 and cooling mediums may be used and that any number of things may serve as the heat sink 26.

Other modifications, changes and substitutions are intended in the foregoing, and in some instances, some features of the invention will be employed without a corresponding use of other features. For example, the heating system 24 and cooling system 26 may be open loop, closed loop, or hybrids of the same. Although it is preferred that the refrigerant system 10 be closed loop, it is understood that the refrigerant system 10 may also be open loop, closed loop, or hybrids of the same. Further, the heating system 24, refrigerant system 10, and cooling system 26 may but are not required to have associated reservoirs for accommodating fluctuating loads. Further still, the turbine 14 may or may not include flow diverter members disposed therein, and, if included, any number of different shapes, configurations, and flow patterns may be used. It is of course understood that all quantitative information is given by way of example only and is not intended to limit the scope of the present invention. 

1. A combination, comprising: a housing; a refrigerant source operably connected to said housing; a refrigerant disposed within said refrigerant source; a shaft, at least a portion of said shaft being disposed within said housing; a first rotor blade affixed to said shaft within said housing; at least one first conduit disposed within said housing, said at least one first conduit being disposed downstream of said first rotor blade; and a second rotor blade affixed to said shaft within said housing, said second rotor blade being disposed downstream of said at least one first conduit.
 2. The combination of claim 1, wherein said housing has a front, upstream end and a rear, downstream end, and further comprising: a first flow diverting member disposed within said housing between said first rotor blade and said second rotor blade, said first flow diverting member being configured to direct said refrigerant downstream of and forward of said first rotor blade, said shaft passing through said first flow diverting member.
 3. The combination of claim 1, wherein said first rotor blade extends a first distance radially from said shaft, and said second rotor blade extends a second distance radially from said shaft, said first distance being less than said second distance.
 4. The combination of claim 1, further comprising: at least one second conduit disposed within said housing, said at least one second conduit being disposed downstream of said second rotor blade; and a third rotor blade affixed to said shaft within said housing, said third rotor blade being disposed downstream of said at least one second conduit.
 5. The combination of claim 4, wherein said housing has a front, upstream end and a rear, downstream end, and further comprising: a second flow diverting member disposed within said housing between said second rotor blade and said third rotor blade, said second flow diverting member being configured to direct said refrigerant downstream of and forward of said second rotor blade, said shaft passing through said second flow diverting member.
 6. The combination of claim 4, wherein said first rotor blade extends a first distance radially from said shaft, said second rotor blade extends a second distance radially from said shaft, and said third rotor blade extends a third distance radially from said shaft, said first distance being less than said second distance, and said second distance being less than said third distance.
 7. The combination of claim 1, wherein said refrigerant has a boiling point at 14.7 psi that is less than or equal to approximately 32° F.
 8. The combination of claim 1, wherein said refrigerant is selected from the group consisting of R-11, R-12, R-13, R-134 a, R-142 b, R-152A, R-290, R-410 a, R-404 a, R-600, R-600 a, a hydrofluorocarbon, a chlorofluorocarbon, CO₂, ammonia, nitrogen, freon, and combinations thereof.
 9. The combination of claim 1, wherein said first rotor blade comprises at least approximately 20% of a material selected from the group consisting of aluminum, composites, plastics, and combinations thereof.
 10. A combination, comprising: a closed loop system, said closed loop system comprising: a refrigerant storage container; a refrigerant disposed within said refrigerant storage container; a turbine operably connected to said refrigerant storage container for receiving said refrigerant from said refrigerant storage container; a condenser operably connected to said turbine for receiving said refrigerant from said turbine, said refrigerant storage container being operably connected to said condenser for receiving said refrigerant from said condenser; and said closed loop system not including a compressor; and a heat source for supplying heat to said closed loop system, said heat source being disposed to provide heat to said refrigerant when said refrigerant is in said turbine; and a heat sink for removing heat from said closed loop system, said heat sink being disposed to remove heat from said refrigerant when said refrigerant is in said condenser.
 11. The combination of claim 10, wherein said turbine comprises: a housing; a shaft, at least a portion of said shaft being disposed within said housing; a first rotor blade affixed to said shaft within said housing; at least one first conduit disposed within said housing, said at least one first conduit being disposed downstream of said first rotor blade; and a second rotor blade affixed to said shaft within said housing, said second rotor blade being disposed downstream of said at least one first conduit.
 12. The combination of claim 11, further comprising: a first flow diverting member disposed with said housing between said first rotor blade and said second rotor blade, said shaft passing through said first flow diverting member.
 13. The combination of claim 10, wherein said first rotor blade extends a first distance radially from said shaft, and said second rotor blade extends a second distance radially from said shaft, said first distance being less than said second distance.
 14. A method, comprising: (a) providing a turbine having a front, upstream end and a rear, downstream end; (b) passing a refrigerant through a first stage of said turbine so that said refrigerant passes a first rotor blade affixed to a shaft and disposed in said first stage; (c) after step (b), redirecting said refrigerant so that said refrigerant passes a first point within said turbine downstream of and forward of said first rotor blade; and (d) after step (c), passing said refrigerant through a second stage of said turbine so that said refrigerant passes a second rotor blade affixed to said shaft and disposed in said second stage.
 15. The method of claim 14, further comprising: (e) after step (d), redirecting said refrigerant so that said refrigerant passes a second point within said turbine downstream of and forward of said second rotor blade; and (f) after step (d), passing said refrigerant through a third stage of said turbine so that said refrigerant passes a third rotor blade affixed to said shaft and disposed in said second stage.
 16. The method of claim 14, wherein step (b) comprises: passing said refrigerant through said first stage of said turbine so that said refrigerant passes said first rotor blade affixed to said shaft and disposed in said first stage, said refrigerant having a boiling point at 14.7 psi that is less than or equal to approximately 100° F.
 17. The method of claim 14, wherein step (b) comprises: passing said refrigerant through said first stage of said turbine so that said refrigerant passes said first rotor blade affixed to said shaft and disposed in said first stage, said refrigerant having a boiling point at 14.7 psi that is less than or equal to approximately 32° F.
 18. The method of claim 14, wherein step (b) comprises: passing said refrigerant selected from the group consisting of R-11, R-12, R-13, R-134 a, R-142 b, R-152A, R-290, R-410 a, R-404 a, R-600, R-600 a, a hydrofluorocarbon, a chlorofluorocarbon, CO₂, ammonia, nitrogen, freon, and combinations through said first stage of said turbine so that said refrigerant passes said first rotor blade affixed to said shaft and disposed in said first stage.
 19. The method of claim 14, further comprising: after step (b) and before step (d), passing said refrigerant through a heating section so that said refrigerant comes into heat exchange contact with a conduit disposed at said heating section.
 20. The method of claim 19, further comprising passing water through said conduit. 